RE: ported vs non-ported choke
Since I provided that advice I'll try to close the loop.
Ported chokes reduce recoil by venting gas in a direction other than straight out the barrel. A law of physics (sorry - don't remember which one) is that for every action there is an equal and oposite reaction. If the entire charge (shot, wad, and escaping gas) is discharged straight out the barrel, the reaction is the gun moving ("kicking") in the opposite direction equal in force. Ported chokes disperse the gas in perpendicular to the shot charge, thereby lessening the felt recoil and muzzle jump. Velocity isn't appreciably affected, since the gas is vented at right angles as the shot leaves the muzzle. The rub is a much louder muzzle blast, which isn't an issue with a one-shot turkey gun where nobody is aroung to feel the effects. Take that same gun to a duck blind and you loose friends fast.
You asked about the "wad stripping" effect. The shot charge (shot encased in the wad) as it goes down the barrel is subject to spinning. If the shot charge exits the muzzle while spinning the centrifical effect of a spinning charge results in some of the shot being spun out and dispersed in a wider fashion, effectively worsening the pattern. Ported chokes slow or stop this spinning effect, resulting in the shot exiting the muzzle in a straight-line manner (ie not spinning), withresultant improved and denser patterns.
Why more hunters don't use them, I can't answer.
Federal makes a load (flight control wad)with a wad designed to stay with the shot much farther downrange. The front of the wad is solid plastic (no petels), with smallpetelsof plastic that stick out in the rear like airbrakes. The rear petals allow the wad to stay with the charge longer in flight, keeping the shot together longer leading to tighter patterns. These loads are said to work best with non-ported chokes, that don't strip the wad, which makes sense. I shot some prior to the season and noted that the wad was shot much further than other loads, so I think the conceptworks. I even saw and heard the wad hitting the target at 35 yards, and that was out of my ported Star-dot choke.
Good luck
Mouthcaller.